The present invention is directed to semiconductor packaging and, more particularly, to a method of attaching an insulated bond wire to an electrical contact pad.
Semiconductor devices with high pin counts and multi-tiered wire looping present higher opportunities for wiring short circuits. As a result, insulated bond wires are often used as an alternative to traditional bare bond wires. Conventional techniques for attaching the bond wire to an electrical contact pad include the formation of a free air ball (FAB) on a first end of the bond wire using an electric flame off (EFO), bonding the FAB to a first contact pad (first bond), followed by a looping formation, and concluding with a wedge or stitch bond (second bond) formed at the second end of the bond wire on a second contact pad.
Insulated wires can create a problem for the second bond formation because the insulating material can act as a barrier between the core of the bond wire and the contact surface on the substrate, lead frame, or the like. This leads to a poor electrical connection as well as poor physical attachment and bond strength at the second bond.
It is therefore desirable to provide a method for more reliably attaching the second end of an insulated bond wire to an electrical contact pad.